The reader further asks, "when controlled breeding programs can get results in a relatively much shorter period of time, wouldn't more rapid evolution itself be a good species survival trait and thus have been selected for?"

Although there is fierce debate as to how fast natural selection can proceed and if natural selection is still proceeding in humans due to our technology, there is a short answer. Speed is probably not very important in natural selection and is certainly not the only consideration in natural selection.

There is a danger in mutation. Most mutations do not help the species survive. A species and an environment exist in balance with each other. Populations simply adapt to their current surroundings and to changes in those surroundings. They do not necessarily become better in any absolute sense over time.

A change in the environment may require a change in the species for that species to survive. But if a mutation spreads too quickly across an entire species it may prove maladaptive to the species if the environment undergoes a further change. More diversity in mutations and hence change is probably better than speed in a mutation becoming widespread in a species.

Related to this question, an important principle of natural selection is that a trait that is successful at one time may be unsuccessful at another. This principle was demonstrated by the classic experiments of C Paquin and J Adams of the University of Laval in Quebec, Canada, and published in Nature in 1983.

Paquin and Adams developed a yeast culture and maintained it for many generations. Every so often a mutation would appear that allowed its bearer to reproduce better than its contemporaries. These mutant strains would crowd out the formerly dominant strains. Samples of the most successful strains from the culture were taken at a variety of times.

In later competition experiments, each strain would out-compete the immediately previously dominant type in a culture. But interestingly, some earlier strains could out-compete strains that arose late in the experiment. Competitive ability of a strain was always better than its previous type. Yet competitiveness in a general sense was not increasing.

The success of any organism depends on the traits of its contemporaries. There is likely no optimal design or strategy for most traits, only ones based on chance such as the competition and the environment.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au